Late-life depression (LLD) is a major public health concern. It is associated with substantial impairment and disability in social and cognitive domains, increases risk for and exacerbates the severity of comorbid medical conditions [4-6], elevates risk for suicidality, and is a significant contributor to mortality. These associations and risks take on greater significance because LLD is commonly under-diagnosed and inadequately treated. Epidemiological research also suggests the presence of social inequalities in LLD. Socioeconomic status (SES), usually assessed by measures of education, income, wealth, occupation, and/or neighborhood characteristics, is associated with risk of depression in older adults (=60 years). Indeed, these risks appear to widen with age, with older adults of lower SES having markedly elevated risk for depression. Evidence is mixed about racial/ethnic inequalities. Whereas rates of LLD are higher among White males than among African-American and Hispanic males, older White males appear to have lower levels of depressive symptoms than older African American males. Furthermore, there is evidence that African Americans and Hispanics, in general, experience higher rates of chronic depression. The relationship between race/ethnicity and depression is itself, influenced by gender, income, and education. This application is for a small research grant (R03) to conduct secondary data analyses to investigate social and racial/ethnic inequalities in outcomes of antidepressant treatments in older adults. These analyses emerge from an initial study in which Cohen et al., (2006) reported SES (as measured by census tract median household income) was a significant moderator of antidepressant treatment in two clinical trials in which all subjects received high quality care. The proposed research will expand on this work by conducting an investigation of possible social inequalities in the effectiveness of PROSPECT (Prevention of Suicide in Primary Care Elderly: Collaborative Trial), a multi-site randomized clinical trial of an intervention (pharmacotherapy, interpersonal psychotherapy, and case management) for the treatment of LLD. We will also investigate whether the relative effectiveness of the intervention depended social inequalities in positive changes in social support during treatment and/or the extent to which patients took advantage of various components of the intervention. The proposed research will benefit from its use of data from a randomized clinical trial that was conducted in "real-world" primary care settings and included a heterogeneous sample of depressed older adults, as well as the availability of multiple measures SES and race/ethnicity at the level of individuals and the neighborhoods in which they lived. Results of this research may yield insights about: 1) the social factors that influence the effectiveness of treatments, even when controlling for access and the quality of treatment;2) the clinical and public health needs of population subgroups;and, 3) the need for methodological changes in future clinical trials. More generally, we expect this research will make an important contribution to our understanding of health disparities. Late-life depression is a major public health concern in that it is associated with increased risk for functional disability, suicidality, and mortality. Expanding on preliminary research, which suggested social inequalities in the effectiveness of antidepressant treatments, the proposed research will investigate social inequalities (as measured by socioeconomic status and race/ethnicity) in the effectiveness of a primary care intervention for reducing depressive symptoms, hopelessness, and suicidality, and improving functional status in older adults. Results of this research may yield new insights about: 1) the social factors that influence the effectiveness of treatments, even when controlling for access and the quality of treatment;2) the clinical and public health needs of population subgroups;and, 3) the need for methodological changes in future clinical trials.